Reference is first made to FIG. 1, a schematic of a human heart and its four heart valves. Mitral valve 2 lies between the left atrium 1 and the left ventricle 5 to control blood flow unidirectional from the left atrium 1 into the left ventricle 5. A dysfunctional mitral valve does not close properly and leads to regurgitation where blood flows backward from the left ventricle 5 to left atrium 1 during systole. Mitral regurgitation can cause pulmonary congestion and a dilated left ventricle which can ultimately result in heart failure and mortalities.
The mitral valve 2 structure is shown in FIG. 2. Mitral valve is a complex load bearing structure that consists of annulus 2.1, anterior leaflet 2.2, posterior leaflet 2.3, chords 2.4, papillary muscle 3, and the underlying left ventricular myocardium. The anterior 2.2 and posterior leaflets 2.3 are attached to the annulus 2.1. The annulus 2.1 is an anatomical structure joining the leaflets and the left ventricle wall. It is divided into the fibrous annulus in the anteromedial section and the myocardium annulus in the posterolateral section, according to annulus 2.1 histology. The chords originate from the papillary muscles 3 and insert into the leaflets. They prevent the leaflets from prolapsing into the left atrium during systole. The papillary muscles 3 are attached to the wall of the left ventricle.
The normal closure of mitral valve is shown in FIGS. 4 and 3, there is no gap between the anterior and posterior leaflets without regurgitation. When the closure of mitral valve is shown in FIGS. 5 and 6, there is a gap between the anterior and posterior leaflets, and the blood flows back from the left ventricle to the left atrium through the gap in systole, thus the backward flow phenomenon is called mitral regurgitation
At present, the common mitral valve repair techniques include triangular or quadrangular resection, slide annuloplasty, ring annuloplasty, chordal cutting and transposition, artificial chord use and, recently, percutaneous technologies. The success of this therapy depends on an understanding of the delicate force balance between the leaflets with lower reliability, resulting to 50% of the mitral regurgitation recurrence in 5 years after the treatment.